Electromagnetic radiation proof electrical connectors



Nov. 14, 1967 M. F. WALTHER 3,352,982

ELECTROMAGNETIC RADIATION PROOF ELECTRICAL CONNECTORS Filed March 15, 1965 I 3 Sheets-Sheet 1 NV ENTOR .MARK E WA LTHER 6M) MW TORNEY AGENT Nov. 14, 1967 M. F. WAI THER 3,352,982

ELECTROMAGNETIC RADIATION PROOF ELECTRICAL CONNECTORS Filed March 15, 1965 v 3 Sheets-Sheet 2 United States Patent 3,352,982 ELECTROMAGNETIC RADIATlON PROOF ELECTRICAL CONNECTORS Mark F. Walther, Newburg, Md., assignor to the United gtates of America as represented by the Secretary of the avy Filed Mar. 15, 1965, Ser. No. 440,041 9 Claims. (Cl. 260-5107) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to electric cable connectors and more particularly to an electric cable connector and filter system, for use in high energy fields, that provides protection from radio frequency energy and also provides elimination of transient low frequency energy generated by radio frequency arcing whenever making or breaking separate electrical contacts.

Modern weapons are often carried in or on a launching apparatus which can be mounted on land, sea or air vehicles. The weapon is usually passive until an electrical actuating signal is supplied from the launching vehicle. The signal usually actuates one or more electroexplosive devices in the weapon by heating a resistance wire in contact with a small charge of explosive powder which, when ignited, initiates a chain of explosives or propellants. For reasons which will be explained later, it should be emphasized that there is usually one electroexplosive circuit associated with each weapon called the firing circuit which when energized activates the weapons circuits and devices which results in weapon launching or some other final action.

The use of electroexplosive or igniter squib assemblies in areas which have high energy fields present creates a serious problem, since, if suflicient energy is picked up by the electrical firing circuit associated with the squib, a premature firing may occur. A premature ignition could cause serious damage to associated weapons or injury and loss of life to personnel handling the missiles. Weapons and weapon systems are often designed without any provision with respect to radio frequency energy. Oncea weapon is operable, it is necessary to determine if it is sensitive to certain environmental conditions. One of these conditions, of course, is susceptibility to radio frequency energy. To determine this, each weapon had to be tested in full scale tests. In these tests, loading and handling procedures had to be performed to attempt to achieve the highest coupling of radio frequency energy into the electroexplosive device that was likely to occur in service. If a dangerous condition was present under these conditions, then the necessary corrective measures were determined. Therefore, it would be desirable to have a simple, foolproof and reliable apparatus or technique that would positively preclude the possibility of premature ignition under any circumstances and thus, eliminate or drastically reduce, the extensive testing required in this area.

Exhaustive work has been done in recent years to preclude hazards of electromagnetic radiation to weapons and ammunition used by the military. Weapons usually had some protection from electromagnetic hazards for the electroexplosive-devices contained therein by the natural barriers of the shield provided by the weapon skin, compartments and in some cases by electrical breaks in the circuit provided by safing and arming mechanisms. These means were often insufiicient and were often a failure with respect to the principal firing circuit because of electrical leads external to the weapon. Where a positive means was employed for combatting the problem, most prior art apparatus uses the principle of frequency discn'mina- 3,352,982 Patented Nov. 14, 1967 tion; that is, they incorporate filter circuitry that rejects or dissipates radio frequency energy and passes the direct current or low frequency firing signal. In order for the frequency discriminator technique to accomplish satisfactory rejection or attenuation, it is necessary for the firing signal to be unique from any spurious signal introduced at the input of the frequency discriminator. Usually, units using the frequency discriminator technique work well for electroexplosive circuits which are confined to the interior of the weapon, but are not effective in the aforementioned principal firing circuits when the missile is connected to the launching apparatus. During connection of two electrically separate units, which are in a field of high radio frequency energy, arcs may be created due to the difference of potential between the separate units, and this radio frequency arcing may generate frequencies below the cut-off frequency of the frequency discriminator of sufiicient current magnitude to energize the igniter. Because of the ineffectiveness of frequency discriminators in arcing environments, it would be desirable to have an apparatus or technique that would not be susceptible to radio frequency arcing and which would be simple and reliable in operation.

The disclosed apparatus utilizes the advantages gained by the use of a frequency discriminator filter and eliminates its disadvantages. This is accomplished by providing a unique connector construction and filter arrangement that positively prevents radio frequency arcing energy from flowing through the firing circuitry during connecting procedure. This accomplishes protection for the firing circuit of electroexplosive devices from premature actuation from spurious electrical influences which could lead to premature actuation. Since the firing circuit is in two parts; one for the weapon, and one for the launching vehicle, it is necessary to provide shielding at the connection point or separation point of this circuit. The connector disclosed provides a simple, foolproof switching technique that provides the proper sequence of switching operations for the safest operation without the necessity of multiple separate switching operations. All of the switching sequence takes 'place at the proper times as the male and female connector are mated or unmated. In addition, the connector provides a radio frequency barrier that effectively prevents'any energy from entering the female portion of the connector whenever the connector unit is separated, and it also has a provision for waterproofing the female connector wherever it is disconnected from the male connector portion.

An object of the present invention is the provision of an improved electrical connector combination that may be used in high energy fields.

Still another object of the present invention is to provide an improved electrical connector that is simple and inexpensive.

Another object of the present invention is the provision of an electrical connector combination that suppresses and eliminates energy transfer to internal circuitry.

A further object of the present invention is to provide a protective device which permits safe, reliable and rapid connection to external circuitry in high energy fields.

Another object of the present invention is the provision of an electrical device that permits electroexplosive devices to be connected to external control circuitry without danger of detonating.

Still another object of the present invention is the provision of a technique of connecting missiles having electroexplosive devices to fire and control circuitry whenever the missile is in a high energy radio frequency field.

A further object of the present invention is the provision of an electrical connector that is easily and readily installed in any missile circuitry that has an electroexplosive device.

Still another object of the present invention is the provision of an improved electrical connector that is adaptable for use in aircraft missile circuitry.

Another object of the present invention is the provision of an electrical connector unit that has a waterproof female connector portion.

Another object of the present invention is the provision of an electrical connector that permits safe operation and connection to an electroexplosive device in high energy radio fields.

Another object of the present invention is the provision of an electrical connector apparatus that provides the female portion of the connector with a radio frequency barrier.

Another object of the present invention is the provision of an electrical connector that acts as a switch which prevents direct current and/ or audio frequency signals generated by radio frequency arc from reaching the weapons electroexplosive device, and that also gives protection from radio frequency energy before the weapon is connected to the control circuitry.

A further object of the present invention is the provision of a standardized technique of protection for an electroexplosive device which is energized by power sources external to the weapon.

Still another object of the present invention is the provision of an apparatus that allows a single frequency discriminator filter for many weapons.

A further object of the present invention is the provision of an apparatus that supplies the necessary protection with minimum increase in weight in the missile part of the system.

Still another object of the present invention is the provision of a technique that is applicable to many weapons sensitive to electromagnetic energy and which eliminates the need of full-scale testing to determine that the weapon is insensitive to electromagnetic energy.

A further object of the present invention is the provision of a technique that may be applied to many weapons in order to provide a standardized connection procedure for many weapons subject to high energy radio frequency fields.

Another object of the present invention is the provision of a mating connector that does not require rotation to effect a connection.

A further object of the present invention is the provision of holding the connectors in their coupled position by spring-loaded members.

Still a further object of the invention is the provision of an electrical connector unit that has connector segments radially distributed so that circuits can be changed while the connector physically remains in the connected position.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings wherein:

FIG. 1 illustrates a cross-sectional view of the male connector portion of the electrical connector assembly and shows its internal arrangement of elements.

FIG. 2 illustrates a cross-sectional view of the female connector portion of the electrical connector assembly and shows its internal arrangement of elements.

FIG. 3 illustrates a cross-sectional view of the construction of the electrical contacts in the female connector portion of the electrical connector assembly.

FIG. 4 illustrates a cross-sectional view of a modification of the female connector portion of the electrical connector assembly and shows an arrangement of elements to provide waterproofing of the connector.

FIG. 5 illustrates a cross-sectional view of another waterproofing modification for the female connector portion of the electrical connector assembly.

FIG. 6 illustrates a cross-sectional view of a spring electrical contact arrangement for the female connector portion of the electrical connector assembly.

FIG. 7 illustrates a perspective view of a modification to the connector for positioning the connectors at positions relative to one another.

FIG. 8 illustrates a cross-sectional view of the modified connector of FIG. 7.

With reference to FIG. 1, there is shown a male connector portion indicated generally as numeral 10. The body of the male portion of the connector is constructed in the form of a metallic hollow cylindrical member that is threaded on one end. A cap member 12 having internal threads 13 is fastened onto the body member 14 by means of these threads. The cylindrical cap member is formed with a necked down portion opposite the threaded end. This necked down portion is drilled to a size that corresponds to the outside diameter of the shielded cable which is to be connected to the electrical contact 16. The cap member 12 is constructed in this way so that the shield of the shielded cable (not shown) may be soldered around the periphery of the washer 72 between cap member 12 and body member 14 in order that good electrical and physical connection is obtained from cable to male connector portion when the cap member is tightened by its threaded portion against washer 72. The center conductor of the shielded cable, shown as 11, is electrically fastened to the ring-like electrical contact member 16.

Body member 14 has a locking shoulder 17 approximately half-way down its length. At the end opposite the cap 12, the body member 14 is formed with a substantially rounded end at its outer periphery; this construction facilitates connection to the female portion 20 of the connector. Immediately inside the hollow cylindrical member 14 is an internal shoulder which abuts an insulating sleeve member positioned inside the connector body 14. The insulating sleeve member 15 is constructed so that it has an annular chamber 19. At one end of body member 14 and adjacent the rounded portion 18 is an electrical ring-like contact member 16 which is flush-mounted in the insulating sleeve member 15. This member 16 may be flushmounted to the insulating member by any suitable means. Also, the insulating member 15 is fastened to the interior wall of member 14 by suitable fastening means. The shielded cable member for the male connector portion 10 is not shown in the drawing since it is felt that it is not necessary for disclosure of the electrical connector.

The female portion of the connector, indicated generally as numeral 20, has a collar portion which is flush-mounted with the missile body member 21. The missile body member 21 and the collar of member 22 are fastened together by any suitable means which will provide good electrical and mechanical connection. A metal stud 23 is centrally positioned in the chamber of the metal cup-shaped female connector portion 22. This member has two necked down portions. One of these necked down portions is threaded and fastened into the base of the chamber wall by means of these threads.

The lower portion of the metal cup-shaped female connector portion 20 has a necked down portion 33. This necked down portion is formed with a cylindrical cable chamber. The shielded cable is connected to the wall of the female connector by soldering the cable shield around the periphery of the necked down portion 33.

The metal stud member 23 has positioned on its outer periphery two electrical ring-like contacts 25 and 29, respectively. Ring-like contact member 25 is not insulated from the stud member; whereas the ring-like electrical contact 29 is insulated by an insulating sleeve 27 which fits over one of the necked down portions of the metal stud member; the insulating sleeve shown as numeral 27. Electrically connected to contact 29 and passing through the insulating member is an output lead 31 which may be connected to the igniter or squib unit. This connection is not shown in the drawing.

A metallic curtain 24 formed of spring-like fingers is positioned inside the metal cup-shaped single female connector portions chamber. This metallic curtain 24 is electrically and physically connected to the inner wall of the cup-like member 22, and extends toward the opening contacting the metal stud member adjacent the chamber opening. The metallic curtain fingers are shaped to bend away from the end of stud 23. The purpose of the curtain is to provide a radio frequency shield for the contact members 25 and 29 whenever the connector portion is unmated from connector portion 20.

Referring now to FIG. 3, there is shown a more detailed section of the structure of the electrical ring-like contact members 25 and 29, respectively. As shown, the convoluted expansion spring is held on the metal stud member 23 by a C ring, sections 26 and 28, respectively. This sort of structure permits extremely good electrical contact, since the electrical contact may be made at a number of points around the periphery of the ring rather than at a single point. For case at assembly of C ring 26 to the central stud a joint should be made in the C ring 26.

The electrical lead 31 passes through a passageway provided in the wall of container 22 and connects to the igniter assembly.

In operation, as the male connector portion 10 is mated with the female connector portion 20, the rounded end portion 18 will first come in contact with the stud member 23. As the connectors are further mated, a portion 18 will contact the metallic curtain 24 and the respective fingers will be forced outwardly to ride against the outer peripheral wall of the hollow cylindrical member 14. If any radio frequency field is present and it is of sufficient magnitude to cause arcing between these respective elements, no current can flow to the squib assemblies (not shown) through lead 31, since there will be no electrical contact with the electrical contact 29. As the member 10 is further mated with member 20, the electrical stud member 23 will slide along the wall of the insulating sleeve member and will eventually reach the flush-mounted electrical ring-like contact member 16. As the respective connector members are further mated, the electrical contact 16 will come into electrical contact with the electrical contact 25 which is always at ground potential. This contact 25 positively grounds any difference of potential which may exist between electrical contact 16 and the stud member 23. As the member 10 is fully mated with the contact member 20, electrical contact 16 will mate with its electrical contact counterpart 29 in a completely radio frequency-free chamher. With the sequence of contact making as explained above, there is no possibility of an unknown potential existing between the contacts 16 and 29 which may cause a current to flow through the output lead 31 and which could permit a predetonating condition to exist.

Whenever the two connectors are unmated, the female connector, by means of the metallic curtain 24, will always provide radio frequency shielding for the electrical contact 29 at all times. The male connector portion 10 by its construction also provides radio frequency arc protection for its electrical contact member 16, since it is positioned inside the hollow cylindrical member 14. Contact member 16 is also physically protected by this arrangement.

FIGS. 4, 5, 6, 7 and 8 of the drawings show other embodiments of the electrical connector assembly. FIGS. 4 and 5 have a construction which Waterproofs the female connector portion 20, whereas FIG. 6 shows another contact arrangement and FIGS. 7 and 8 shown a connector construction in which a circuit insulated from the shield of the connectors can be switched to different circuits.

Referring now to FIG. 4, there is shown a washershaped diaphragm 36 which may be constructed of rubber or similar material positioned at the opening of the connector portion 20. The outer edge of diaphragm 36 may be fastened to the collar of the connector by means of machine screws 34 and washer 35. Other suitable fastening means may be used, if desired. The inner portion of the diaphragm 36 is rounded and thickened. This portion is in contact with the metal stud member 23 and the outer edges of the metallic curtain spring fingers 24. This rubber section fits or lies between the edge of the fingers and lies adjacent to the top surface of the stud 23, thereby providing a moisture-proof enclosure for the opening of the female connector portion 20.

FIG. 5 shows a different arrangement of water-proofing and radio frequency shielding protecting the entrance of the female connector portion 20. The radio frequency shield 41 is formed so that it is fastened by means of machine screws to the outer surface of the collar of the metal cup-shaped female connector portion 22 and its inner end makes electrical and physical contact with the metallic stud member 23. Positioned on top of the radio frequency shield 41 and in intimate contact with its top surface is a rubber diaphragm 38 having similar characteristics to diaphragm 36. It should be noted that the inner portion of diaphragm 38 physically touches and grips the stud member 23. This sort of connection provides an efiicient moisture sealing means and prevents any water from accumulating in the chamber of the female connector portion 20. The outer peripheral edge of both the rubber-like diaphragm 38 and the radio frequency shield member 41 are held to the collar of the female connector 22 by means of machine screws and washers.

Referring now to FIG. 6, there is shown an embodiment of the invention that provides rings of spring fingers 43 positioned on the outer surface of the electrical ring-like contact members 25 and 29, respectively. This sort of construction permits better electrical contact to be maintained between the female contact members and its coacting electrical contact member 16. With this sort of construction, a positive electrical contact is assured once the contacts come into intimate contact.

Referring now to FIG. 7, there is shown an embodiment of the invention that provides contacts for two electrically isolated circuits plus a grounding circuit. This embodiment might be employed as a low voltage power output fixture. The electrical contacts 101 and 102 are sectors so that the sectors 103 and 104 are also mounted opposite in insulating sleeve 105. An indexing mechanism consists of plunger 106, spring 107 and screw 108 installed in the central stud of the connector.

Referring now to the co-acting plug of FIG. 7 which has two contact members 109 and 110 which mate with the contact sectors and a groove and 4 holes 111 that co-act with the female connector. Additional details of the connector are shown in FIG. 8. In operation, the rotation of the male connector, FIG. 7, in steps would switch. the output of the male connector of two separate two-wire circuits which are inputs to the female connector 7 and in this way provide two off positions.

The connector disclosed provides a positive means of isolating, shielding and moisture-proofing a firing circuit or output circuit of a weapons system. The use of such a connector provides means to standardize the firing circuit for many different types of weapons. The connector provides an unbroken radio frequency shield, even though the male connector is disconnected from the female connector. Also because of this shield, there would be no need to install frequency discriminator filters in the weapon or manual contact switches for the purpose of eliminating direct current and/ or audio frequency signals which may be introduced 'by radio frequency arcs. In addition to the configuration shown, the external firing circuit would not introduce radio frequency energy into the interior of the weapon so that all other electroexplosive devices would be safe with no more than the protection afforded by the weapon shell. The connector provides a structure that mechanically isolates the electroexplosive circuits from tampering or inadvertent touching of external objects through which electrical energy could be transmitted to the electroexplosive circuits.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. An electrical connector apparatus that provides for safe connection of its component parts in high energy radio frequency fields comprising first connector having an annular chamber first electrical contact means positioned in said annular chamber said first electrical contact means electrically tied to a first electrical circuit means second connector having an internal chamber stud means positioned substantially in the center of said internal chamber and extending substantially the full length of said internal chamber,

second and third contact means electrically and mechanically fastened to said stud means second electrical circuit means electrically coupled to said third contact means and barrier means electrically and mechanically attached to the wall of said internal chamber and in electrical contact with said stud means for enclosing said second and third electrical contact means,

whereby the mating of the first connector with the second connector brings the annular chamber into intimate contact with the stud means and the first and third electrical contacts physically together to provide a complete electrical connection between the first and second electrical circuit means.

2. The electrical connector apparatus of claim 1 wherein said stud means comprises a generally cylindrical shaped metallic member having first and second necked down portions said first necked down portion having positioned thereon a ring-like insulating member and said second necked down portion having threads thereon.

3. The electrical connector apparatus of claim 1 wherein said barrier means comprise a plurality of spring-like fingers said fingers shaped in the form of a vase-like chamber having the neck portion of in physical contact with said stud means.

4. The electrical connector apparatus of claim 1 wherein said barrier means comprise plurality of spring-like fingers shaped in the form of a vase-like chamber and a rubber-like washer having a thickened portion on its inner periphery said washer positioned to enclose said internal chamber whereby the rubber-like member forms a waterproof cover for the second connector.

5. The electrical connector apparatus of claim 1 Wherein said barrier means comprises metallic washer-shaped element having its inner periphery turned downwardly into said female connector to form a venturi-like chamber 3 said venturi-like chamber extending substantially into said female connector to contact said stud means at said washer-shaped elements narrowest constriction and 5 rubber-like diaphragm means molded to said metallic Washer means whereby the metallic washer means forms a radio frequency barrier and the rubber-like diaphragm forms a moisture-proof barrier. 6. The electrical connector apparatus of claim 1 wherein said second and third electrical contact means comprise ring-like contact members, and spring fingers positioned on the outer wall of said ringlike contact member and extending substantially to the contact members edges. 7. An electrical connector apparatus for use in high energy radio frequency fields comprising male connector means having a first electrical contact means and a locking means positioned internally 2 thereof,

said locking means comprising an encircling groove internally of said male member, female connector means having second electrical contact means and detent means positioned internally thereof, and

2') barrier means operatively connected to prevent radio frequency from entering the area of the second electrical contact means whereby the locking means and detent means co-act upon mating of the male and female portions of the connector for permitting rotation of said male and female portions with respect to one another while preventing inadvertent uncoupling. 8. The electrical connector apparatus of claim 7 wherein said locking means, comprises four holes positioned 90 apart having their centers perpendicular to the longitudinal axis of the male member, whereby the male member may be rotated when mated with the female member to bring the first electrical contact means and second electrical contact means in intimate contact in two of the four positions, thereby causing the respective circuits connected to the first and second contact means to be electrically disconnected without unmating the male connector means from the female connector means. 9. The electrical connector apparatus of claim 8 wherein said four holes are interconnected by a shallow groove.

References Cited ROBERT S. MACON, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

D. SMITH, JR., Assistant Examiner. 

1. AN ELECTRICAL CONNECTOR APPRATUS THAT PROVIDES FOR SAFE CONNECTION OF ITS COMPONENT PARTS IN HIGH ENERGY RADIO FREQUENCY FIELDS COMPRISING FIRST CONNECTOR HAVING AN ANNULAR CHAMBER FIRST ELECTRICAL CONTACT MEANS POSITIONED IN SAID ANNULAR CHAMBER SAID FIRST ELECTRICAL CONTACT MEANS ELECTRICALLY TIED TO A FIRST ELECTRICAL CIRCUIT MEANS SECOND CONNECTOR HAVING AN INTERNAL CHAMBER STUD MEANS POSITIONED SUBSTANTIALLY IN THE CENTER OF SAID INTERNAL CHAMBER AND EXTENDING SUBSTANTIALLY THE FULL LENGTH OF SAID INTERNAL CHAMBER, SECOND AND THIRD CONTACT MEANS ELECTRICALLY AND MECHANICALLY FASTENED TO SAID STUD MEANS SECOND ELECTRICAL CIRCUIT MEANS ELECTRICALLY COUPLED TO SAID THIRD CONTACT MEANS AND BARRIER MEANS ELECTRICALLY AND MECHANICALLY ATTACHED TO THE WALL OF SAID INTERNAL CHAMBER AND IN ELECTRICAL CONTACT WITH SAID STUD MEANS FOR ENCLOSING SAID SECOND AND THIRD ELECTRICAL CONTACT MEANS, WHEREBY THE MATING OF THE FIRST CONNECTOR WITH THE SECOND CONNECTOR BRINGS THE ANNULAR CHAMBER INTO INTIMATE CONTACT WITH THE STUD MEANS AND THE FIRST AND THIRD ELECTRICAL CONTACTS PHYSICALLY TOGETHER TO PROVIDE A COMPLETE ELECTRICAL CONNECTION BETWEEN THE FIRST AND SECOND ELECTRICAL CIRCUIT MEANS. 